Until now, hard disk drive (HDD) offers an advantage of storing data at low cost. At the same time, other types of memories such as flash memory caught up and now represent a threat to HDD. Flash memory belongs to a category of non-volatile memories (NVM). It allows the data to be stored even when power is down or off.
The flash memory market is getting bigger but the cost per gigabit (Gbit) is higher than that of HDD. HDD technology is moving towards patterned media where bits are made by lithography processes. The cost per Gbit for HDD should not be increased by more than 10% or 20% in order to remain competitive. This is one of the major challenges facing the HDD technology.
A current trend is to develop non-volatile memories (NVM) beyond flash memory, which is cheaper and has a high performance. Magnetoresistive random access memory (MRAM) and phase change random access memory (PC-RAM) represent good candidates for future NVM. It is expected that spin transfer torque magnetoresistive random access memory (STT-MRAM) devices can have a cell less than 10 nm based on high magnetic anisotropy materials used for the storage layer, such as ordered FePt-L10. However, this is not possible for flash memory.
In order for MRAM to be industrially viable, there is a need to increase the memory storage density of MRAM devices.